Plastic binding of hard cased books



Dec. 4, 1951 1 DE FLoREz ET AL PLASTIC BINDING oF HARD cAsED Booxs 5 Sheets-Sheet l Filed May l, 1948 L. DE FLOREZ ET AL PLASTIC' BINDING OF HARD CASED BOOKS Dec. 4, 1951 3 Sheets-Sheet 2 Filed May l, 1948 NVENTORS A [mls de Warez.

i' di Warez gjvefz E. ('igrg HTTORNEY DGC- 4, w51 DE FLoREz ET AL 2,577,568

PLASTIC BINDING OF' HARD CASED BOOKS Filed May l, 1948 3 Sheets-Sheet 3 INVENTORS luis 'de ez Feier de 714716Z augen Z. (ivre :BY

HTTOR N EY Patented Dec. 4, 1951 PLASTIC BINDING E HARD cAsED. Books Luis de Florez and. PeterY de Florez, Pomfret, Conn., and 0`wen L. Gore, Great' Neck, N. Yg, assignors, by mesne assignments, to The de Florezv Company, Inc., a corporation of Dela- Application May 1, 1948, Serial No. 24,494y 91 claims.; (ci. 11;-1=

This invention relates to the manufacture ofy books, and in a particularly important aspect, to the making of hard cased books, which are gem erally characterized by having an attached cover of a relatively Stiff or heavy nature. Such. cover or casing usually consists of cloth faced boards or the like, with the cloth or other covering mate'- rialextending across the back edge or spine of the book, the structure being further characterized by a grooved or creased` hinge at thejoht of each side element with the back edge covering.

Books of this nature ordinarily require the inclusion of certain elements and manipulative operations in the early stages of their manufacture for proper application and permanency of the ultimately attached casing or cover. Thus, .for instance, the Stages of assembling and binding the book prior to the rounding and other steps that precede the ultimate casing operation, per se, have customarily provided for the inclusiony ofv the so-called end papers, which are relatively heavysing1e folded sheets that have to be pasted.l in by hand at each, end or face of: the book. body and that have the outer leaf of each ultimatelyA adhered to the inner face of, the corresponding cover board. y

Furthermore after binding thesi'gnaturesand rounding and backing their back edge, the liningup operation has involved they attachmentv of, al` piece of fabric, usually crash, over the back edge and with sidewise protruding flaps, allarrangedfor ,adhesive attachment to the casing. so as to co,- operate in holding the latter in place and so as to strengthen the hinges. As mentioned above it. is. customary, before the crash is applied, to round and back the rear edge of the book body, especially to bend the rear portions of the outermost signatures into a flaring or harige-like projection along each side ol'the back edge so that the cover boards` may nt close to the assembled body of leaves andso that the hinge portions of thevr cover fabric. (Whether cloth, paper or other material) l willhave ample freedom oiV motion without-any tendency. to become torn or pulled out of place.

In these and other respectsA the manufacture of hard cased books involves special' featuresr of; construction and operation which may not be rcquired in other methods of book binding and' cas.- ing, for example as followed in making books (such as telephone books and many Others) that are Simply cased with paper or like wrappers.

Although procedural combinations of thesort contemplated by this invention may find' application elsewhere, they are primarily designed for. the production of hard cased books,l and are.in

tendedto serve,.in a noveland eicient manner, theparticular. requirements of book structures to which such a. casing can be iinally applied. It will be understood that although the term binding."is sometimes loosely employed to denote the entire operation of securing the leaves of a book together and applying a casing or the like to it, or is indeed sometimes' identied only with the casing, operation,` a more Specic signicance ofv the vterm (generally followed herein) is in reference tothe particular set of operations Whereby an unsecured assembly of'leaves, such as a collection of unsewn signatures, is firmly and eiiectively fastened together so as to constitute an. integral book, assembly with all of the leaves. held against removal from vcach other, the binding,v operation per se being thus distinct from the subsequent steps that are more directly preliminary to or involved in the application of the casing.

Heretofore in the manufacture of books, notably of the type described,` the completev procedure hasl been in many respects discontinuous, involving tedious-and time-consuming hand operations, requiring accumulation of printed sheets, or signature bundles or book assemblies at one4 or another stages of partial completionV and thus representing, in many respects, a disproportionately expensive process. book printed in a multiplicity or" separate, socalled signatures which must beindividually folded, and then, for each book, collected, but the` endpapers are commonly pasted by hand to thev outer leaves of the first and last signatures. Thereuponl the books are individually transferred to sewing machines, where the signatures of each.

assembly are sewn individually (in succession) and to each other. The assembled and' sewn books are subjected to the so-called smashing operation. Further steps include applying some adhesive tothe sewn back edge (to complete the binding per se), .then trimming other edges of the book body, and finally rounding and-backing it, the last mentioned step being followed by lining-up, which involves the application of hot glue Thus not only is the,v

as'zarsc out introducing additional steps or affecting various other steps in the procedure. We have now discovered, however, a complete and integrated procedure the elements of which are so correlated and interdependent as to constitute a continuous process which can best be illustrated by a flow diagram, as of the sort embodied herein. In accordance with our discovery, the book sheets, the book blocks and the book assemblies enter into the procedure and are gradually progressed in a continuous manner, the aim being -to start with a web of paper and end with a finished, cased and complete book.

A similarly important object of the invention is to provide a new and improved procedure for book manufacture, whereby the successive operations are simplified and rendered entirely or at least in much greater part continuous and whereby stronger and more durable characteristics in the binding and'casing are afforded. A further object is to enhance the efliciency and decrease the cost of book manufacture, particularly in the binding, rounding, backing 'and lining-up operations, and other objects are more specifically to provide methods minimizing the number of separate steps, preferably eliminating certain operations altogether and affording a more ruggedly bound book which is better adapted for casing and for long service after it is ultimately cased and completed.

Still further objects are the provision of new procedural combinations and sub-combinations for expediting various operations and sets of operations in the art of book making, and in an important, complete sense, a chief aim of the invention is to provide an essentially continuous process for making hard cased books or the like, throughout all operations from the actual printing step or steps to the ultimate casing-in.

To these and other ends, a specific procedure, including a number of variations thereof is described hereinbelow by way of example and thus for illustrative disclosure of the principles and features of improvement; but it will be understood that one or more of various steps in the process may be carried out in other ways, and that various sub-combinations of the method may be employed under other circumstances or in other environments.

In the annexed drawings:

Fig. 1 (consisting of Figs. 1-A, l-B and l-C) is a view of the nature of a flow diagram illustrating one embodiment of the preferred process, of which the continuously successive portions are represented by illustration of correspondingly progressive operations on the paper or on the book assembly, all in a generally schematic manner;

Fig. 2 is an enlarged schematic view of one stage in the assembly of the book block;

Fig. 3 is an enlarged View of certain devices past which the book block is carried in Fig. 1; and

Figs. 4 and 5 are enlarged views of the book as it 'leaves the successive backing and lining-up operations respectively, of Fig. 1.

Although limitations of space compel Fig. 1 to be divided into a plurality of views, they represent in fact a single, continuous process and can be conveniently identified simply as Fig. 1.

The complete procedure shown is intended to cover the entire sequence of operations from printing to ultimate casing-in, except for the omission of certain minor steps which have no outstanding relation to the invention and which will be fully understood by persons skilled in the art. It will be appreciated that elements of apparatus appearing in the drawing are purely schematic in that for the most part they are 5 intended to afford a recognizable indication of the type of operation at various stages, rather than to restrict the system to any particular device which might be employed to perform such operation.

By way of general introduction, the complete and preferably more or less continuous procedure, may include the original step of printing indicated at I, the assembling of the printed leaves or other sections into a collection that may be conveniently designated as a book block, i. e. at II, the co-assembly of the end papers at I2, and the step of engaging and holding the block in its assembled condition, i. e. as at I3, for further successive operations. The latter include an edge trimming or smoothing step I4, adhesive application I5, drying I6, outer-edge trimming I'I, rounding and backing I8, lining-up I9 and ultimate casing-in at 2U. Notably important aspects of the present invention reside in the discovery that improvement and simplication of the entire procedure may be realized by taking advantage of certain inter-relationships among the several steps, such as shown and such as are more fully described below. For at least the most part, these inter-relationships represent special features of cooperation beyond and in addition to the desirably continuous character achieved by the process more or less throughout its course, such continuous character being nevertheless one to which an important, and indeedfor many purposes essential, contribution is made by the correspondingly continuous nature of the several individual steps.

For instance, although the original printing operation may be performed in the customary manner with at bed presses and to provide separate signatures, a particularly convenient step is to print the entire book continuously on a constantly traveling web of paper (withdrawn from a supply 29), which is appropriately sectioned and folded for collection into an assembled book block. One apparatus suitable for the printing step involves features and combinations described and claimed in the copending applications of Edwin K. Smith, Serial No. 24,210, led April 30, 1948, now abandoned, and Luis de Florez and Edwin K. Smith, Serial No. 24,174, filed April 30, 1948, and involves passing the web 30 first in engagement with a set of flexible printing plates 1 3l on a wide, endless, steel belt 32 such that all of the pages for one side of the sheet are printed by a single cycle of the belt 32 as the web passes one section of the long impression cylinder 33. The

web moves over the turning and reversing bars 60 34 and then travels past another set of printing plates 35 mounted along side of the first set on the belt 32 to imprint the opposite side of the web so that the latter, on leaving the press at 30a may have all of the pages for the complete book 65 printed on it by a continuous operation. The pages, for economy of space and paper may be aligned in rows lengthwise of the web and thus can be severed into corresponding strips side-byside as shown at 40 (in the first step of the col- 70 lecting operation II), and the separate pages in the strips may then be physically defined by an accordion folding operation as shown at 4I.

Although the several strips can be separately folded and the resulting page groups then as- 75 sembled in proper order, another procedure, as

means of turning bars 42 so that aplural-layerl web 43 is provided for the accordion folding operation 4I. In. either case the web. is. appropriately severed in. correspondence with the printing cycles, and the resulting assembliesconstitute completebook blocksllll. Where the strips are separately 'folded each block consists of successive single folds, while with. the specic process shown the blocks lll are made up ofy a like accordion arrangement having several layers (e. g. three, in the drawing) at the folds. It will be understood that in any given case the printing plates 3|, 35.v are arranged to suit the ultimate folding and 'assembling operation so that theactual succession of individual leaves in the block provides the printed pages in desired order.

Thev book blocks dll are moved along in continuous series, and as shown at I2, suitable end papers, 4E, lll may be associated with each passing block, the relation of lthe end papers being also shown in the exploded View, Fig. 2; The end papers are thus incorporatedV directly against and as part of each block, but without any adhesive attachment thereto. It will be understood that in the case of larger booksV more than one press operation may be necessary, but in any event the primary stages just described comprise the assembly of a complete set of printed leaves together with the end Vpapers in the proper order to form a completely assembled but entirely unfastened book block 48 as shown at the next stage I3.

Although stager I2 might employ the conventional structure ofend papers as double sheets disposed with their folded edges at the back edge 50 of the book block, it is equally feasible in most cases tofuse simply one'ortwo single sheets (as shown) at each end or even to employ double sheets folded the other way, i. e. with theirfolded edges at the outer or forward edge of the book block (uppermost in the drawing), in complete contradistinction to the present, invariable practice of book manufacture. In other words, in most instances of the invention the folds of the end papers are unnecessary and indeed' undesirable in the nished book; such folds are preferably cut olf during manufacture, i. e., if at the. outside, they are'removed when the outside edge is trimmed. It may be noted that the convenience of assembling the endpapers with the book` blockand without pasting ,themv to the end leaves of the latter is made possible by 'the cooperation substituted for the steps indicated in sectionsn Ill.

and II of the drawing. In such case the several signature sheets, for example, are printed in the usual manner and are then folded toprovide the separate signatures (i. e., each having 4, 8, 16, 32 or other usual number of leaves), which are thereupon collected into assemblies corresponding to individual books, as in a gathering machine of the sort commonly used. Preferably, in accordance with the present invention, these operations would be modified to include the end papers in the gathering-machine step, i. e., soA

that. as the signatures are gathered-for each book the end: papers would be included, respectively the first. and last. places of eachk completed assembly. As. stated. above, in the preferred practice of the process it is unnecessary andusually undesirable.- to paste either end paperto the adjoining signature; the papers are simply as',- sembled inV proper relation, without attachment, as indicated at stage I2 of the drawing.

It is at present greatly preferred, however, to employ a more effectively continuous printing and' assembling operation than is involved in the separate printing and subsequent collecting of' signatures. expedited by the continuous nature of steps of the sort illustrated at Ill and II in the drawing, but further operations. in the course of binding are peculiarly facilitated by avoiding folds ofY more than. two or three layers at the back edge, e; g. by avoiding themultiple-layer folds which necessarily occur at the back edges of signatures. Indeed a further and especially usefulv alternative to the indicated arrangement of printingandlassembling. is to provide for actual severing of the individual pages or leaves as single sheets so that I the entire` book block'has nofolds at any edge at all. In this, and likewise, in other cases, the end papersl can consist ofl merely a pair of separate sheets at each face of the block, or indeed a single sheet alone may be used, it being thus understood' that the term end papers is intended` herein to include generically theV use ofV a single end' sheet (i. e. to. such extent, if any, as the end papers need be identied separately from' the other leaves of the book), which is the sheet that is ultimately.adheredv to the inside of the front orrear cover of the final casing; Furthermore although in. some cases it is preferred to make the end papers of heavier stock than the ordinary leaves of the book, the entire procedure is often expeditedby simply providing an extra leaf or leaves at suitable localities in the sheet or web used in the printing operation, to constitute the end papers.

Although other means of holding and trans- -L porting the book block 48 for further operations may be employed, a convenient arrangement is. to engage it in.t a clamp 52 which acts compressively on opposite faces of the block soas to leave the edges, particularly the back edge 50; acces-- sible for further operations. Preferably, toc,.the same clamp can be employed to holdY the block through at least many, and indeed practically all, of the succeeding steps, and the clamp thus also f serves toV transmit motive power to the block where eiciency is enhanced by performing one or another of the operations on the moving book.

With the book block i8 held in the clamp 52 (detailed illustration of the latter being omitted for simplicity in the succeeding portions of the drawing, although it will be understood that in practice this or another clamp is preferably there used), the block is then advanced and carried through the edge finishing station Id, where the back edge is constituted as a smooth, usually plane surface in which the edge of each constituent leaf is fully and squarely exposed, i. e. at the level of such surface. Although heretofore cutters of. the guillotine type have been extensively used for trimming other edges of assembled books-than the back edge, it is greatly preferred that in the present process the operation on the back edge of the block be carried` out with rapidly moving cutting elements which repeat-l edly traverse the block and advance Vacross it. As: will beA further apparent hereinbelow, Fmax- Not only is the entire process greatly' imum effectiveness of the present binding method appears to be attainable only Where the adhesive, as applied, can both reach and penetrate the cut edge of each individual leaf. In the use of knives of the guillotine type, the block is held stationary under direct pressure and the cutting blade is forced through the block in a single powerful motion. Not only is this operationpoorly adapted for inclusion in a continuous or other desirably rapid process, but the resulting transverse surface is excessively smooth and indeed of a glazed or glossy character, which it has now been found to be relatively unsatisfactory for adhesive binding. Although a moderately smooth surfaceis desirable in many cases, there should be opportunity for edgewise penetration of the adhesive, and preferably some provision for control of the smoothness of cut, e. g. to accord with the character of the paper as explained below. Generally speaking, guillotine trimmers are incapable of adjustment or change to provide anything less than an extremely smooth cut.

In consequence the operation designated I4 is preferably accomplished with rapidly and repeatedly moved cutting elements. In some cases the elements may constitute a rotary knife (successively presented portions of the knife periphery being conveniently considered as successive elements), but evidence indicates that at least in some cases a rotary knife may have the disadvantages, though in a less degree of a guillotine cutter, giving an excessively smooth cut across the leaves or otherwise preventing the attainment of a uniform, square exposure of each leaf edge, suitable for the adhesive.

Accordingly one preferred operation is first to slice off a thin layer of the back edge 50 of the continuously moving block 48 with a band saw 54 (i. e. as the block moves by) and then to advance the book across a rapidly moving and conveniently diagonally disposed abrasive surface such as the sanding band 56, whereby the saw-cut edge is converted to a surface of relatively high smoothness which now seems preferable for optimum results. It has been found that in this manner the desired constitution of the back edge is achieved, with the individual leaf edges adequately exposed in the common plane of such surface.

Although it might supercially appear desirable to proceed with the relatively rough surface left by the band saw, i. e. as furnishing more tooth for the subsequently applied adhesive, experience indicates that the roughness is occasioned by relatively loose fibers which may become embedded in the adhesive but have no holding strength relative to the leaves of the block. With a smooth edge, there is little looseness of the fibers and much better opportunity for penetration of the adhesive edgewise into the individual leaves, for maximum holding effect. The optimum degree of smoothness depends on the character of the paper, as more fully explained below, and an advantage of the abrasive treatment resides in the accurate control Which it permits for reaching any desired smoothness.

In the edge nisliing operation, all folds at the back edge are effectively cut away or removed. Where the block consists of signatures of the older sort each having a multiplicity of superimposed folds of paper, the cut made by the saw should be relatively remote from the back edge of the assembled signatures, in order to be sure that all folds are removed. In some cases, even Fith the existence of folds at the back edge of the block and particularly Where there are only sin--4 gle folds as derived by separately subjecting each page strip of a printed web to the accordion folding step, the finishing operation can be perfected with a simple sanding or grinding process, i. e. without any actual saw or knife cut; for simplicity of definition herein, the term cutting operation is employed broadly to designate any removal of paper, whether by saw or knife or merely by abrasive treatment alone. Indeed it is conceivable that in some instances with a block of separate sheets having no folds at the back edge, the assembly may be so jogged or otherwise treated as to afford a sufficiently smooth back edge surface with all leaf edges fully exposed at the level of the surface, so that the cutting operation (which might involve abrasive treatment alone, or both sawing and abrasive treatment) can be dispensed with. Ordinarily, however, it appears more efficient to rely on some positive surfacing step as assuring the desired condition and shape of the edge surface.

After passing a rotating brush 58 which removes loose particles of fiber and abrasive grit from the surface 50, the clamped block 48 is further advanced for application of adhesive to the surface 5U, preferably in such manner that the applied adhesive penetrates edge-wise into each leaf and at the same time comprises an integral lm or coating over the entire back surface, integrally connecting the adhesive portions that have penetrated (e. g. to a desired extent, which need be relatively slight in most, cases) within the several leaves. For some limited purposes a f variety of glues or other adhesives may be used,

e. g., such as heretofore employed for securing tablets or blocks of sheets that do not receive a hard casing; but an important and peculiarly cooperative element of our preferred, complete process, i. e. to yield durable results and indeed to afford a way of realizing certain subsequent operations which lead to the ultimate production of a hard-cased book and which cannot be effectively performed with glue-type adhesives, in-

l volves the application of an adhesive having specio characteristics such as described immediately below. Ths type of composition, which is now greatly preferred in carrying out the continuous operations shown, comprises a thermoplastic adhesive material, advantageously dispersed as an aqueous emulsion, i. e. an emulsion of the material in Water. More particularly the plastic substance constituting the body of the adhesive is preferably water-insoluble and should also be of a somewhat resilient nature, i. e. should have some small degree of elasticity or resilience (when it is finally dry, ser, and entirely cold) for maximum wearing qualities in the ultimate book. Unless otherwise stated, references herein to insolubility of the adhesive substance mean insolubility in water.

The thermoplastic nature of the adhesive is not only of advantage in application and in insuring the desired integrity and bonding of the adhesive material during the drying operation,

but cooperates peculiarly in the subsequent mechanical deformation of rounding and bending the back edge structure to the shape commonly needed for a hard cased book. Thus by operating at an appropriate temperature, the thermoplastic adhesive yields satisfactorily without losing its integral character or its bonding to individual leaves during the mechanica1 deformation, and yet at ordinary temperatures it has sufficient rigidity (although some elasticty as mentioned vary asta-56s above) to keep the block, and thus the book, in essentially its desired shape and inter-relation of leaves at all times.

Finally the use of water as a suspending agent for the adhesive seems of special advantage, too. While in some cases other 'media for suspension or solution maybe employed, and can be satisiactorily removed in the drying operation, water is believed to be peculiarly appropriate (as 'a vehicle 'for dispersion or suspension of thev insoluble adhesive substance) for optimum penetration of the adhesive into the fibers. Extensive investigation tends to confirm this characteristic of water-carried adhesives of the type herein contemplated, and while 4the precise reason for the effect is not positively knownrand 'the present invention is therefore not to be vbound by any theory, it is thought that the nature oipaper as derived from a water ysuspension of pulp nbers renders it peculiarly rsusceptible to softening and capillary penetration, e. g. temporary separation of the constituent bers, by water That is to say, water is lmore or less readily absorbed by any kind oi paper, and in the corresponding absorption of awater-carried adhesive, the particles or drops or other elemental portions of the adhesive substance itself appear to be physically carried by the water into and among the bers. To some extent, in the case of an emulsion, the paper may have a filtering action, in that the Water tends to penetrate further than the suspended adhesive substance; `nevertheless the adhesive penetration seems to be greatly v facilitated by the water, and the Aresult is a 'sat- -isfactory structure which is understood to provide a somewhat decreasing adhesive density 'in the paper, from a maximum at the extreme outer edge to a lower (though useful) valuefsomewhat short of the extreme vlimit of water penetration. In any event a full and eiective bond is obtained between each leaf and the overlying film (across the back surface), and thus among all vof 'the individual sheets or leaves.

Very preferably in most cases eiiort vshould be made, as by tight clamping of =the book blo'ckand if necessary by regulating the 'iiuidity of the adhesive material, to keep 'the 'latterffrom becoming veryV far inter-leaved, so to speak, between the adjacent sheets of the block, since investigations indicate that a maximum holding power is rafforded by edgewise bond of lthe adhesive film to each sheet, yor "at least that the holding power is fully as effective and there is less interference with the opening ofthe book in use 'and indeed less tendency ofthe sheetstotear (i. e. by `actual breakage of the paper) under unusual stresses, than when reliance is placed on any substantial extent of flatwise adherence between the leaves near theback edge. The extent to which the adhesive should penetrate the individual leaves 'may somewhat with different circumstances, such as grades vand thicknesses 'of paper, 'size of the book, 'the type of ultimate casing and 'the character of the v.intended use of the book. Ordinarily and atleast `for economy in the use of vthe adhesive, the distance of such penetration need only be very small, for example so that a substantial density of the insoluble plastic is established to a distance of 0.001 inch or so from the back edge in each leaf, with the water carrier penetrating somewhat further. In any case the optimum penetration can be ascertained, 'if adjustment appears necessary, by very simple tests with sample book blocks in any particular 'course vof "operationse It has found that'with adhesives of thesort speciedby way of example below and with a proper snioothness'and leaf-edge exposure at the back edge surface 5U 'as determined bythe surfacing operation M, a relatively substantial layer or coating' may Kbe applied to the back edge surface, without capillary penetration 'in the leaves beyond a useful distance, and without excessive iiow of adhesive between sheets (e. g; further tlia'n 0.010 inchfor sofrom the back edge) where the block is held moderately tightly as by the clamp 52.

-An important correlation between the adhesive application l5 andthe surfacing operation lIl resides in 'the variation of adhesive penetration with the character 'of the 'paper and the smoothness of the back edge surface of the block. For instance, with relatively non-absorptive papers a back edge surface of only moderate smoothness is satisfactory and may often be most desirable to secure the optimum 'endwise bond of each leaf. With 'many papers of high or considerable absorptiveness, however, an extremely smooth surface -is preferred, to insure that a satisfactorily v'retentive 'film is formed and remains across the back of theblock; a roughly cut, absorbent paper is apt to soak vup so much adhesive that only a very 'thin film can remain across the edges. With such a out, the juxtaposed edges lof the leaves provide a minutely uneven contour which tends vto aggravate the weakness of any 4iilm so thin that its outer v'face (as well as'its under side) follows such'contour. It will now be readily understood "that the smoothness "of cut in operation i4 can be regulated according to the absorptiveness of the paper, 'for instance by employing finer or coarser grit in the abrasive element 56, so as to provide precisely the desired extent of absorption roperation M.

'tion and adherence of the subsequent crash and of the liq'ui'd adhesive composition 'in any given c'ase.

nifor'mity of 'adhesive penetration and bonding is Adesirable 'and indeed under ordinary circumstances an adequate control 'of lthese factors 'and ci the extent of penetration now appears to be atta'inablewith proper control of the thickness ofthe applied adhesive layer and ofthe character of the edge 'surface as provided `by the cutting Furthermore for `proper disposifor proper attachment of the ultimate casing, uniformity in the adhesive 'film is 'very advantageous, `as well as reasonably `careful control of the vthicknessof such'lm. yAs'willnow be readily appreciated by persons 'skilled the art, a film that is too thin may provide only a weak binding of lthe pages together, while a film `of excessive thickness may aifor'd only a poor or otherwise improper sort of bond between the block and the subsequently attached structure, i. e. the crash and the casing, especially in that the operation of drying an overly thick coating may produce imperfections in it.

Thus a particularly important feature of the invention, cooperating in various significant ways with other steps as indicated above and elsewhere herein, involves the regulated application of 'the described adhesive coating to the back surface of the book block. Various mechanical arrangements may be employed for such application of adhesive, Vfor instance so as to apply a relatively substantial coating of controlled thickness. By way 'of illustration the drawing shows schematically an arrangement suchl as 'described and Aclaimed 'in the patent application of Peter deFlorez, Serial No. 770,726, filed August 26, 1947. A pair'of spaced rollers 60, 6| are disposed to rotate half submerged in a bath 62 of the liquid adhesive, so that each book block 48 passes across them in succession, their upper surfaces moving in the samedirection and at the same rate as the blocks. The first roller 60 eiTectively forces liquid adhesive against and throughout the back edge of the v block for insurance of the desired penetration.

l heavy coating of the liquid adhesive on the back surface 50 of each block while providing a sharp break of the material 'as the trailing end of the block leaves the rod 63.

While various arrangements as indicated hereinabove, may be employed to regulate the thickness of the coating, peculiarly satisfactory results are achieved with a further device described and claimed in the aforesaid application of Peter deFlorez, Serial No. 770,726, involving a wiper or doctor element 65 having spaced, upstanding ridges 66 extending in the direction of book travel (as also shown in the detail view, Fig. 3). The element 65 is of thin flexible material or is otherwise resiliently constructed so that as the book travels by, the upper edges of the ridges 66 are pressed with moderate firmness against the actual back surface 50 of the block 48. The height of the ridges 66 above the plane upper surface of the doctor element 65 is equal to the thickness desired for the adhesive coating on the surface 50.

Since with the applicator 60 an excess of adhesive is preferably applied, the doctor element 65 thus wipes off the excess and leaves only a coating of the precise thickness desired, which is automatically gauged to the edge of the book itself, by virtue of the ridges 66. There is no dependence on an exact positioning of the book relative to any stationary element, and the fluid nature of the adhesive coating in effect obliterates the paths of the ridges once the book has left the element 65, whereby a smooth coating of the desired thickness is obtained. As indicated hereinabove, it is essential for proper penetration and for proper constitution of an integral bonding layer across the surface that the coating be relatively substantial in thickness as distinguished from the thin sort of nlm that would be left if a full scraping or wiping operation were used. At the same time, for effective binding of the pages and for smooth and secure tough, adherent, thermoplastic film across and in engagement with the edges of the leaves in the book block; the formation of such iilm is promoted by the heat employed in the drying operation |6. Thus one preferred material is the latex of vinylidene chloride and acrylonitrile polymerized together (in approximate proportions of 85 parts and 15 parts respectively), which., is known as Saran F-122 (made by Dow Chemical Co.) such material being further modied with a plasticizer as stated above, e. g. to a total amount of about 25% based on the weight of the polymerized constituents.

Other compositions that may be used in some cases include the so-called Geons (made by B. F. Goodrich), which are emulsions of materials described as special vinyl chloride polymers, and understood to include a straight vinyl chloride polymer, but in most instances to be copolymers of vinyl chloride and vinylidene chloride. Useful adhesive properties are also exhibited, at least to a limited degree, by emulsions of polyvinyl acetate, e. g. straight polymers or inclusive of other substances. If a hot melt adhesive can be employed, there is evidence of utility for material of the nylon family; but substances capable cf and used in aqueous dispersion, are at present preferred, for their special advantages mentioned above.

Following the application of the wet adhesive the bock block is conveniently passed through a drying station I6, i. e. where the adhesive is converted to a relatively solid, set condition, as by suitable evaporation of its water content. Although satisfactory results have been had by employing simple heat drying means (e. g. sources of radiant heat), efficiency of the complete process is enhanced by employing high frequency energy to dry the adhesive. Thus purely for schematic illustration the drawing shows wave-emitting or radiating structure 10, delivering such energy to the adhesive-coated bottom surface of the block 48, the element 10 being in turn energized by connection to an appropriate oscillator or other electromagnetic wave generator schematically shown at 1|.

The general principles underlying drying of water-carried adhesives (under other circumstances) with ultra high-frequency electromagnetic radiation are known, in that the currents or other electrical effects set up by the radiation in the aqueous medium generate (presumably as a hysteresis loss) sufficient heat to evaporate the attachment of the crash later applied, the coating should be uniform and should not exceed a practical limit, a convenient criterion being to make the wet coating as thick as is possible without giving rise to bubbles or other physical disturbance in it during the drying step that follows. For insta-nce, for books of average dimensions (8 vo. size), a coating 0.006 to 0.0'10 inch thick, when wet, has been found suitable; such coating dries and sets to a thickness of 0.004 to 0.006 inch.

Simply by way of example, one type of adhesive composition suitable for application as described is an aqueous emulsion or so-called latex of a copolymer of vinylidene chloride and acrylonitrile, such emulsion preferably including a suitable plasticizer such as dibutyl phthalate, dibutoxy phthalate or a mixture thereof. Compositions of this character form, upon drying, a

water, a result which is achieved in the present process with a maximum of rapidity and einciency since the paper of the book is relatively non-responsive to the radiation, and the heat is localized in the very material to be evaporated. Accordingly by this or other procedure, the adhesive is effectively dried and reduced to a set condition, and to the extent that the drying operation is of a rapid character, the path of travel of the book block through the stage I6 will be relatively short and the efficiency and economy of the process (and of the apparatus for carrying it out) are greatly improved.

If one or more of the outer edges of the book block are to be trimmed, such operation may follow the drying stage I6. Although in some cases guillotine cutters, e. g. a so-called tumbler trimmer, may be used, it is generaly preferable to maintain the continuity of the process as shown at I1 in the drawing. Thus here the now bound blocks 48 may leave the clamps 52 and be advanced (for example'by a screw-type pusher 12 or other suitable means) into a sidewise-moving 'array 13 With their successive side faces in abutment as shown, While suitable cutting means effect the desired trimming. Rotary knives or band knives or band saws or in some cases merely abrasive surfaces, or combinations of saws and sanding belts (as at stage 14) may be employed; for illustration, the drawing shows the top-and bottom edges of the passing book blocks being trimmed by the vertical band saws i4 and the fore edge by the horizontal saw 15. If the rtrimmed edges are to be colored or otherwise decorated, this operation may also be performed on the moving column 13, by spraying the paint or ink through one or more nozzles, one such being shown at TIS.

From the column 13 or directly from `the-dry ing stage if there is Ano trimming, the I'book blocks are then successively passed to the rounding and backing operations generally indicated as the stage I8 in the drawing. vHere the block andespecially its back edge-50 yare mechanically deformed, i. e. Vin the general manner and to the shape 'commonly employed for the manufacture of hard cased books. Although 'certain improved apparatus 'may be used (for example'as disclosed and claimed in the cop'ending patent application -of Edward M. Getzoi, Serial No. 752,099, led June 3. `1947), for very rapid, literally continuous n ltravel of the book blocks through this station,

experience indicates that quite satisfactory results and an effective continuity of progress of the blocks may be had with conventional rounding and backing machinery, involving'flrst apair of rollers TI which 'engage the faces 'of lthe block and displace the inner leaves relative to the 'outer ones to provide 'a rounded contour for the back edge 50. At the station of the rounding rollers il, the successive blocks drop on a register plate Tia where each is re-engaged by a traveling clamp52a. The blocks in succession then advance'to, and momentarily pause upon, the backing iron schematically indicated at T8, which by a sidewise rocking action mechanically VAdeforme the 'back edge of the book to complete 'the rounded configuration with the sidewise projecting lribs `orcreases 19,1% (see Fig. 4) usually deemednecessary for proper application and Yfunctioning of a hard casing, especially with respect Yto the tial adhesive layer that covers the back surface and firmly-holds the back edge of each leaf. The successful combination of this step with the preceding binding and subsequent casing operations l is thus grounded on `the discovery that under -appropriateconditions of such other operations a bound 'page block of the character described may be deformed to 'the Adesired rounded `shape without deranging the binding relation of the adhesive material. Where there are assembled vsewn signatures, the backing iron bends over the outer signatures, i. e. adjacent their respective multiple folds, as individual units, andfsince each Y folded signature is itself of the natureofar thick "booklet for -the like, its folded nature lwould .seem to be peculiarly appropriate or veven 'requisite'in affording 'strength to the bent-over condition 'achieved-by the described operation. u.It is therefore remarkable 'tond not only that a block of individual leaves (securely bound by adhesive across their edges) maybe rounded as -by the means ill to `provide a smoothly curved edge'but especially that the backing operation, which bends over vthe 4leaves to progressively greater aamounts toward the outer corners of the back edge, may be performed by the same means as yused for 'sewn signaturek assemblies, vand' yet Without breaking 'or otherwise disturbing the binding-character of the adhesive which is noWeffectively set across fthe back surface and 'integrally penetrates into theledges of the leaves.

Very preferably the back edge ofthe book, i. e. `the adhesive material itself, should be kept yat `a suitable elevatedutemperature during the rounding and backing operation, so that by virtue of the thermoplastic character of the substance it will 'soften and yield, Without breaking, to the `me'cl'ianical deformation. Experience indicates lthat with adhesives of the yspecific type set 'forth 'by way of example above, `maintenance of this velevated temperature is achieved without suplplemental, heating lmeans where the book comes through Athese stages |8 vvithin,V say, fifteen min- 'utesof the 'time that it leaves the heat-drying locality lli.

-If there is too much time taken intermediate these stations it and IB (as bythe supplemental operations l l, .although the latter-can ordinarily be rapid enough -to avoid vusing too much time), 'infra-red lamps or 4other heating devices (not shown) maybe used with the apparatus `at 18, to insure that the:adhes'ive will respond properly. For instance, itis found that by `disposing vsuch heating means 'to Warm the back edge of each block as it advances -to rounding operation, the adhesive coating is effectively maintained inthe -desired heated condition through both the rounding and backing lsteps. vvFor vrthe specific substance named above, temperatures between 120 F. and `200 F', are satisfactory, operation at thelower end of the range being preferred since at the lvhigher temperatures the plastic is apt to become sticky, requiring vlubrication of the `backing iron or irons with waterto `keep the same from Astick- Aing during operation. on the back edge of `the book.

Once rounded, 'the successive blocks 4B are ,car-

vried through the so-called lining-up operation i9, including the 'application tothe rounded back of a-thinlayer of adhesive Sil, `as by a suitable rotary Aapplicator '81, Vand then the application of the usual portion of crash 82 or like fabric `(Which may 'in some `cases be strong paper rather than woventextile) over the fresh adhesive. For customary casing operations, the piece of crash 82 Ysevered from a supply roll '62d and applied to integrally to the previous coating of adhesive, as by some softening or fusing of the outer surface of the previous adhesive, whereby in effect the crash 82 is firmly secured, through an intermediate, unitary adhesive layer, to the actual back edges of the book block.

Accordingly instead of a water emulsion, the liquid adhesive S here applied may constitute a solution or emulsion of the thermoplastic substance in a suitable organic solvent or the like which will attack or soften the plastic binding film. Indeed it will be appreciated that a further desirable property of the plastic material embodied in the binding adhesive 6| is that (after solidication) it be in effect partially soluble, i. e. subject to softening, in a preferably nonaqueous solvent fluid which can be used as the vehicle of the adhesive with which the crash is attached. To these ends, the film-forming substance of the adhesive 80 may conveniently be a plastic material which is the same as, or closely analogous to the plastic body of the adhesive 6I, i. e. so that the former is soluble or dispersible in a solvent that will soften the applied coating of the latter. In one particular instance of procedure embodying our invention, where the adhesive liquid 6I used for binding comprised an aqueous emulsion of the latices formed of a copolymer of vinylidene chloride and acrylonitrile with a suitable plasticizer such as dibutyl phthalate, an adhesive 80 consisting of a copolymer resin of vinylidenechloride and acrylonitrile in methyl ethyl ketone was notably effective for lining-up.

It will be understood that any of various means may be employed t0 apply the adhesive 80, the device 8| being simply shown as a schematic representation of a suitable applicator. In some 'cases the book block with the crash freshly adhered may immediately pass another applicator (not shown) which spreads a very thin film of the same adhesive on the outside of the fabric, it being found that the individual threads of the crash are sometimes difficult to wet with the rst adhesive film applied by the device 8|, whereas the second application insures their being surrounded by liquid adhesive and thus in effect embedded in it.

At this stage, if desired, the usual head bands may also be applied, eitheraccompanying the crash 82 or otherwise disposed on it, and likewise, if desired, the strip of backing paper that is customarily affixed on the outer surface of the crash. For simplicity these supplemental steps are omitted from the drawing, since the purpose of the head band is largely decorative, and particul larly since the use of backing paper may in most cases be dispensed with where the process of the present invention is employed. That is to say, the primary purpose of the backing paper is to prevent the usual glue with which the crash is attached and which invariably soaks through the crash, from soaking into the casing itself, especially at later times because the animal glue is hygroscopic and in moist conditions becomes fluid enough to damage or deface the back strip of the casing.

In the present process the successive blocks 48, with the attached crash 82 are preferably progressed through a drying operation (e. g. using hot air) following the lining-up sequence I9, and l since the resulting, set adhesive is of an insoluble nature and is preferably incapable of re-dispersal .as an emulsion or otherwise in the presence of any water or moisture that might later come in .contact with it, there is no danger of adhesive being subsequently soaked into 'or through the casing from the outside of the crash 82. In consequence the primary function of the backing paper is obviated by the present procedure. Indeed the backing paper is undesirable in many cases, since it tends to prevent rapid evaporation of the solvent from the plastic adhesive.

Finally the book blocks 48 now carrying the crash 82 and such other oi alternative structure as may be desired, advance in continuous succession to the casing-in operation 20. This step may be performed in a customary manner, for example, by applying previously prepared casings to the successive book blocks, the structure of the casing and the precise steps of applying it being mechanically the same, if desired, as heretofore performed in older methods. The casing-in operations, however, are an inherently significant feature of the complete sequence embraced by the invention, e. g. in that the latter is peculiarly designed for the attainment of an effective casingin step to provide a hard-cased book of exceptionally durable character, and in that the casing, instead of being adhered to folded end papers that transmit localized strain to the outer leaves of the outer signatures, is attached only incidentally to end leaves 46, 4l which in the block are connected solely by the adhesive binding, whereby the actual effective connection between the casing and block is more or less restricted to the crash (which has its aps adhered to the casing) and the adhesive layer. This last mentioned structure of crash and adhesive is peculiarly adapted to carry the stresses between casing and block, Without localizing the forces in a manner to damage or derange any part of an entire book.

For example, the successive blocks are passed down between a pair of adhesive-carrying rollers 92, which apply a suitable coating of adhesive to the crash flaps 83, 34 and to the outer faces of the end-paper leaves 46, 4l, using a material such as employed at 8i) in stage I9, or alternatively any other suitable adhesive such as starch paste, and then from an appropriate supply 93, preformed casings 90 are applied. In the latter operation the casing is disposed and firmly pressed around the block, so that the crash flaps and the end papers, i. e. the outermost leaves of the book block, are firmly adhered to the casing, with each crash iiap protected by the end paper pasted over it. The resulting structure 94 is a remarkably strong book, more durable and rugged than books made by conventional procedures and yet having all the characteristics of convenience and pleasing appearance heretofore deemed desirable in hard-cased book construction. The individual leaves are securely attached, and indeed considerably more resistant to removal or separation than in the case of sewn books. The attachment of the book block to the casing is also notably more rm and secure than could be obtained with prior constructions, which is attributed in substantial part to the cooperation between the adhesive binding and the crash, and to the reliance on such structure for mutual support of the parts as explained hereinabove and as distinguished from constructions (heretofore deemed necessary) involving a folded paper connection between the outer leaf of each end paper and the adjacent leaf. Finally where an insoluble adhesive of the preferred character is employed, the book is peculiarly resistant to deterioration by moisture, adverse .weather conditions, damage by vermin and other circumstances tending to the deterioraaanwas@ tion: ofi bound books; eitherf before' onf attenv tlreiitv sale?` Iti will;Y be'.- understood; thatlwherea's-.thei-- entire procedure idescribedi provides;v at novel` andi espe= ciallyeconomicallcontinuity ofioperation on coni-1 tinuously/ moving book elementsandbeokl assemblies,1.and-Whereas -thecompletesequenceiis charLAV acterized `vby aapeculiar-and :advantageous coopera tion"w amongalllofithe" stages frornj the unprintedl web of paper to the finished. hard cased'lbooks;- varioussub combinationsl and I:lessor-*secuentes of operations may-i be separately employed#l tocorree sponding'i advantage and*- Withi like realization ofi" novel cooperative interrelationships: 'I1liiis as1indicafted" the iloriginalprinting 'operationanayfbe lof? a* conventional character;l and l aivarietyf of? other-5 modifications may-f be effected in -1 respect to the several?stagillustratediinthe*drawing@` Finally: itisto'-be'fnotedtliatg thelapparatuslsehemetieal shown? inthe drawings-llas been@ selected4k cliieii forpurposes of=illustrationand other; equipment* forV achieving like or correspondingfresults mayfA b'erusedfat#variousi-stagesaA It'x is to -beunderstood that the V-inveritionist net*- limite'd'i to thespecific lprocedres; arrangementsandg compositicnsilierein set; fortli4 by'ffwayof eicample; but may be'carriedoutin other Ways#With-V outfdeparturefiomits spirit; l

11: Inl the" manufacture of bo'oks th'e `stepssoff assembling af multiplicity ofprinted leaves andi endK4 papers;l together' and't Without2 adhesive`- at*- tachment 4'antr'ongg tr`1en'f,to` form2 a book block, treatingthe back; edge-OP the' blockvv to Icon`sti-tiitl=r-- it as aL smoothV transverse surf-ace wherein the edge of each leaf/.incliidng each leaf of the end papers. isusduarely. exposed at the level of said surface, by rapidly and repeatedly moving cutting elements irrengag'ement'with successive portions of said.: edge,- applying tofsaidf; smooth f surface a coating of an insoluble, resilient-,the1tm0e^- plastic adhesive4 dispersed. in, a.. Water emulsion thereof and'a'dapted to" penetrateedgewise into each leaf', drying said adhesive to solidify-'the'. same. rounding-and backing--said=back edge-surf'a'cebyf mechanic-al deformation there'of' While saidadhesivef is in l anat f least! partiallyl plastic state, andi. lining-up said surface` by adhesively attachinga thereto -aportioriofi`bacling fabric; .so

thatithe bookblockmay-befcafsed by applying I thereto'a hard casing and-by-adfhering the inner surfacesL of lsaidha'rdi casingL topo-rtion's @Offsaid end-papersfandbacking; said rounding andback ing opera-tiony includingila'rin'g-l theleaves -of 'the block toward-'- eachsideof l the'a back edgefsnrf'acel to` constitutehinge-dening-- ridges1 atV the sides-of said surface, which ridgesv'are permanent*- ly maintained bytheadhesive'becoming fully set.

2. In the manufacture ofbooks, the steps of establishingV a book block' consisting of amjulti plictyof leavesandhaving a smooth back' edge surface wherein the edge of each leaf is fully exposed at the level of said surface, applying to said smooth surface a coating of an insoluble, resilient, thermoplastic adhesive dispersed in a water emulsion thereof and adapted to penetrate edgewise into each leaf, While controlling said application to maintain a predetermined, uniform thickness of the coating relative to and throughout said surface, the thickness of the applied coating being controlled as aforesaid so that the coating when dried has a thickness throughout within the range of about 0.004 to 0.006 inch, evaporating the Water from the coating, and thereafter and while said adhesive coating is at leastzpartiailyfplastic', rounding. andkv backing the.-A

ad'hesivelyJ-bound block bymechanical deforma-f tionl of* itsb'ack .edgesurfaca said; rounding; and u backing.' operationnincluding haring` theleaves of 1 theLblocletowardeach side ofthe back-.edgesurev face.` toiy constitute hin-gedeiining. ridges. at! the` sides ofisaidsurface; whichridges arerpermanent:

ly maintained-ibytlie adhesive becoming fullyfset.

3.- In; the manufacture of books, procedure-'for converting ani unbound assembly of leaves -into a l,

exposedl at?. theflevel` of L said'` surface, by. cutting procedure :including: moving'an abrasive surface*y across;andintel-engagement:withv successive por tions of said back edge, applying to: the said;Y

moplastic:adhesive-dispersed ina wate'r emulsions thereof andi adapted to penetrate edgewise into"A each: leaf;` saidivadhesive* being.. applied while= clamping-the book:block to prevent-penetrationfA ofi said iadhesivebetweenthe leaves further; than" aboutl 0.501 inchll from. said smoothA backs edge. surfacediiying tlie1adhesivato solidify" the same.. to provideL an adhesively bound: block having# at laye'rf ofv saidl adhesive acrosssaidl surface: bond-fl ed integrallywith portions of :theiadhesveiin .each` leaf, l andi. rounding'.l andi backing! saidf backedge" surface byxme'chanical deformation Withztheiadl hesve at. an elevated .temperatureV which renders-- the adhesive; yieldabl-el.` to Aprevent rupture ofi! the.;

35,1 adhesive bond, said rounding.' and baekingsop-- eration -includingfaringz the 2leaves of-'f the blockitovva'r'd: each side-f of? tl'fiei backf edgesurface tol constitute hinge-demlingy ridgesy at the: sides of" said surface', which-r1idges arepermanentlyl.maine tainedE bythe-,i adhesive.becoming` fully set.n

4l In'K th'e manufacture` ofi books,-` thef st'epsf:v of l establishing a bookblock.l consisting? essentially? offa'lmultiplicityofl separate leavesiandl'having ai. smooth b'aele edge snrfac'eiwherein the edge.: ofi" eaclfileaff-isdsquarelly Vexposedatthe level ofisa'id.

surface, applying to said back edge surfacefand; iniedgewisefadhesive engagement Avv-ith':each'lsaid leaf awaterinsolu-ble adhesivedn flowablefform. to constituteianl adhesive'lay'er vvextending' across roundingland 'baeking'foperation includingl aringthe-fleaves-1ofs-theiblockI toward each sideofthef bach edge sui-'faceta constitute' ridgeSatftheside's f of "said'lsurface for providing -said 'hinge-'defining configuration, andsaid'adhesive thereafterE setiu ting to maintain the said conguration With the leaves bound together by the said adhesive at their back edges.

5. The procedure of claim 4 which includes the step of adhering a portion of backing fabric to the rounded and backed back edge surface of the book block, by applying intermediate said backing fabric and said surface an insoluble adhesive which is carried in an organic solvent for said first mentioned adhesive and Which is adapted to bond integrally with said first mentioned coating of adhesive. l

6. In the manufacture of books, the steps of establishing a book block consisting essentially of a multiplicity of separate leaves and having a*- smooth back edge surface wherein the edge of ea'ch leaf is squarely exposed at the level of said surface, applying to said back edge surface a thermoplastic, water-insoluble adhesive layer extending across said surface in adhesive engagement with each of the leaves edgewise thereof, and thereafter and while maintaining said ladhesive sufiiciently plastic to permit its yielding without rupture of said layer, displacing the leaves relative to each other to constitute a rounded back edge surface and flaring the leaves toward each side of the back edge surface to constitute hinge-defining ridges at the sides of said surface. to provide a rounded and backed block adapted for application of a hard casing thereto, said adhesive layer thereafter setting to hold said back edges of the leaves in the rounded and fiared configuration.

7. In the manufacture of books, the steps of establishing a book block consisting essentially of a multiplicity of separate leaves and having a smooth back edge surface wherein the edge of each leaf is squarely exposed at the level of said surface, applying to said back edge surface and in edgewise adhesive engagement with each said leaf a water-insoluble adhesive in flowable form to constitute an adhesive layer extending across said back edge surface, and thereafter and while said adhesive is in an at least partially plastic state, rounding and backing the book blockby mechanical deformation of its back edge surface to provide said block with a rounded, hingedefining configuration which is adapted for application of a hard casing to the block, said adhesive thereafter setting to maintain the said configuration with the leaves bound together by the said adhesive at their back edges, said adhesive-applying step comprising clamping the book block during the adhesive application to substantially prevent adhesive penetration between the pages, while controlling application of said adhesive to provide said layer thereof having a substantial thickness adapted to maintain the back edges of the leaves in securely bound relation.

8. In the manufacture of books, the steps of establishing a book block consisting essentially of a multiplicity of separate leaves and having a smooth back edge surface wherein the edge of each leaf is squarely exposed at the level of said surface, applying to said back edge surface aV thermoplastic, water-insoluble adhesive layer extending across said surface in adhesive engagement with each of the leaves edgewise thereof, and thereafter and while maintaining said adhesive suiiiciently plastic to permit its yielding without rupture of said layer, displacing the leaves relative to each other to constitute a rounded back edge surface and flaring the leaves toward each side of the back edge surface to constitute hinge-defining ridges at the sides of said surface.

to provide a rounded and backed block adapted for'application of a hard casing thereto, said adhesive layer thereafter setting to hold said back 4edges of the leaves 4in the rounded and flared configuration, said adhesive-applying step comprising clamping the book block to prevent penetration of said adhesive between the leaves further than about 0.01 inch from said smooth back y edge surface.

9. In the manufacture of books, the steps of establishing a book block consisting of a. multiplicity of separate leaves having a smooth backedge surface in which the edge of each component leaf is squarely exposed, applying to said back edge surface an insoluble thermoplastic adhesive dispersed in a water emulsion thereof and adapted to penetrate edgewise into each leaf, drying the adhesive to solidify the same, rounding and backing said back edge lsurface by mechan- Aical deformation with t-he adhesive at an elevated temperature which renders it yieldable against rupture of its adhesivevbond, said rounding and backing operation providing the book block with a rounded, hinge-defining configura-- tion which is permanently maintained when the adhesive is fully cooled and set and which is adapted for application of a hard casing to the block, and said rounding and backing operation including flaring the leaves of the block toward each side of the back edge surface to constitute ridges at the sides of said surface for providing said hinge-defining configuration which is maintained as aforesaid when the adhesive is set.

LUIS DE FLOREZ.

PETER DE FLOREZ. OWEN L. GORE.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 703,933 Joyce July l, 1902 931,679 Chivers Aug. 17, 1909 1,554,436 Kint Sept. 22, 1925 1,804,392 Alger May 12, 1931 1,867,803 Bredenberg July 19, 1932 1,973,375 Frazier Sept. 11, 1934 1,988,208 Martin Jan. 15, 1935 2,010,810 Bredenberg Aug. 13, 1935 2,069,211 Brown Feb. 2, 1937 2,090,796 Kitcat Aug. 24, 1937 2,151,991 Schramm Mar. 28, 1939 2,463,769 Higgins Mar. 8,1949

2,471,482 French May 31, 1949 FOREIGN PATENTS Number Country Date 890,794 France Nov. 19, 1943 

